Method and device for relay transmission

ABSTRACT

The present invention reduces the complexity and latency in data processing. Disclosed are a method and device for relay transmission. The method includes: a relay terminal device receives a PDU transmitted by a remote terminal device to a network device, where the adaptation layer PDU carries identity information of the remote terminal device, and the adaptation layer PDU is acquired by the remote terminal device by packaging, via a layer 2 adaptation layer, data carried in the adaptation layer PDU; the relay terminal device acquires in the layer 2 adaptation layer the identity information of the remote terminal device carried in the adaptation layer PDU; and the relay terminal device forwards, on the basis of the identity information of the remote terminal device acquired, the data carried in the adaptation layer PDU to the network device.

TECHNICAL FIELD

Embodiments of the disclosure relate to the field of communications, andmore particularly to a method and device of relay transmission.

BACKGROUND

A Device-to-Device (D2D) technology refers to that adjacent terminaldevices may perform data transmission in a close range in a D2D linkmanner without forwarding through a network device. A licensed bandresource may be shared by D2D communication and a cellular system toform a unified hybrid cellular-D2D network. In the hybrid network, partof terminal devices may still work in a cellular communication mode,namely communicating with other terminal devices through a networkdevice, while part of terminal devices may work in a D2D communicationmode, namely performing direct data transmission with the other terminaldevices through D2D links with the other terminal devices.

In addition, data transmission between a network device and a terminaldevice may be assisted through a D2D relay. In such case, a D2Dcommunication mode is adopted between the D2D relay and a D2D terminal,while a cellular communication mode is adopted between the D2D relay andthe network device. The D2D relay receives and forwards data in a halfduplex manner and the modes are switched in a receiving and forwardingprocess.

In a conventional art, a D2D relay relays data transmission between aD2D terminal and a network device through an Internet Protocol (IP)layer (i.e., layer 3). For a received data packet, data relay may beimplemented by decapsulation processing sequentially through layer 1(i.e., a Physical (PHY) layer), layer 2 (including a Media AccessControl (MAC) layer, a Radio Link Control (RLC) layer and a Packet DataConvergence Protocol (PDCP) layer) and layer 3 and encapsulationprocessing sequentially through layer 3, layer 2 and layer 1, which isrelatively high in complexity and relatively long in data processingdelay.

SUMMARY

The embodiments of the disclosure provide a method and device of relaytransmission, which may reduce relay transmission processing complexityand reduce a data delay.

A first aspect provides a method of relay transmission, which mayinclude the following actions. A relay terminal device receives aProtocol Data Unit (PDU) sent to a network device by a remote terminaldevice. The ADPtive (ADP)-layer PDU contains identifier information ofthe remote terminal device and the ADP-layer PDU is obtained throughperforming, by the remote terminal device, encapsulation processing ondata contained in the ADP-layer PDU in an ADP layer of layer 2. Therelay terminal device acquires the identifier information, contained inthe ADP-layer PDU, of the remote terminal device in an ADP layer oflayer 2. The relay terminal device forwards the data contained in theADP-layer PDU to the network device according to the acquired identifierinformation of the remote terminal device.

Therefore, according to the method of relay transmission of theembodiments of the disclosure, the remote terminal device sends theADP-layer PDU to the relay terminal device. The ADP-layer PDU containsthe identifier information of the remote terminal device, and the relayterminal device may recognize the identifier information, contained inthe ADP-layer PDU, of the remote terminal device in the ADP layer andforward the data contained in the ADP-layer PDU according to theidentifier information of the remote terminal device. Compared with alayer-3 relay manner adopted by the relay terminal device in theconventional art, such a manner may reduce processing complexity of therelay terminal device, reduce a transmission delay of relay data andimprove overall performance of a system.

According to an embodiment, a communication interface between the relayterminal device and the remote terminal device may be a first interface,and a communication interface between the relay terminal device and thenetwork device may be a second interface.

According to an embodiment, a user-plane protocol stack, configured forrelay transmission, of the relay terminal device may include layer 1 andlayer 2 and may not include layer 3. In a user-plane protocol stack,corresponding to the second interface, of the relay terminal device,layer 1 may specifically be a PHY layer and layer 2 may only include aMAC layer or may further include an RLC layer and a PDCP layer on thebasis of the MAC layer.

According to an embodiment, in the user-plane protocol stack,corresponding to the first interface, of the relay terminal device,layer 2 may only include a bottom layer and the ADP layer located abovethe bottom layer, and the ADP layer and the ADP layer located above abottom layer in layer 2 of a user-plane protocol stack of the remoteterminal device may mutually be equivalent layers. Or layer 2 mayfurther include an RLC layer and a PDCP layer on the basis of the bottomlayer and the ADP layer, and the ADP may be at any position above thebottom layer. For example, the ADP layer may be located between thebottom layer and the RLC layer.

According to an embodiment, in the user-plane protocol stacks,corresponding to the first interface, of the relay terminal device andthe remote terminal device, layer 1 and the bottom layers of layer 2 maycorrespond to a D2D communication technology adopted on the firstinterface. For example, when the D2D communication technology is aSideLink (SL) technology of Long Term Evolution (LTE), layer 1 may be aPHY layer and the bottom layer of layer 2 may specifically be a MAClayer.

In such a manner, the ADP layers may be arranged in layer 2 of theremote terminal device and the relay terminal device to enable the firstinterface between the remote terminal device and the relay terminaldevice to support any D2D communication technology, thereby improvingcompatibility and extensibility of the system.

According to an embodiment, the user-plane protocol stacks, configuredfor relay transmission, of the remote terminal device and the networkdevice may include layer 1 and layer 2 and may not include layer 3.Layer 2 of the user-plane protocol stack of the remote terminal devicemay include the bottom layer, the ADP layer, an RLC layer and a PDCPlayer and layer 2 of the user-plane protocol stack of the network devicemay include a MAC layer, an RLC layer and a PDCP layer. According to anembodiment, layer 1 of the user-plane protocol stack of the remoteterminal device and layer 1 of the user-plane protocol stack of therelay terminal device are mutually equivalent layers and the bottomlayer and ADP layer in layer 2 of the remote terminal device and thebottom layer and ADP layer in layer 2 of the relay terminal devices aremutually equivalent layers respectively. According to an embodiment, iflayer 2 of the relay terminal device does not include the RLC layer andthe PDCP layer, the RLC layer of the user-plane protocol stack of theremote terminal device and the RLC layer in the user-plane protocolstack of the network device may mutually be equivalent layers and thePDCP layer of the user-plane protocol stack of the remote terminaldevice and the PDCP layer in the user-plane protocol stack of thenetwork device may mutually be equivalent layers.

The ADP-layer PDU received by the relay terminal device may contain theidentifier information of the terminal device. According to anembodiment, the identifier information of the remote terminal deviceincludes an ADP-layer identifier of the remote terminal device or aterminal device identifier of the remote terminal device. According toan embodiment, the ADP-layer identifier may be allocated by the networkdevice in a process of establishing a bearer for the remote terminaldevice.

According to an embodiment, the relay terminal device may recognize theidentifier information, contained in the ADP-layer PDU, of the remoteterminal device in the ADP layer of layer 2 to determine the remoteterminal device corresponding to the ADP-layer PDU.

According to an embodiment, the ADP-layer PDU further contains beareridentifier information of a bearer to which the data belongs.

The bearer may be a radio bearer established between the remote terminaldevice and the network device. According to an embodiment, the bearermay include a first bearer between the remote terminal device and therelay terminal device and a second bearer between the relay terminaldevice and the network device. The first bearer and the second bearermay correspond to the same or different bearer identifier information.

According to an embodiment, the bearer identifier information of thebearer may include a bearer identifier or a Logical Channel Identifier(LCID). For example, the bearer identifier information of the bearer mayspecifically be a bearer identifier of the first bearer.

In a possible implementation mode of the first aspect, the action thatthe relay terminal device forwards the data contained in the ADP-layerPDU to the network device according to the acquired identifierinformation of the remote terminal device may include the followingactions. The relay terminal device generates a layer-2 PDU correspondingto a second interface according to the identifier information of theremote terminal device, the second interface between a communicationinterface between the relay terminal device and the network device. Therelay terminal device sends the layer-2 PDU corresponding to the secondinterface to the network device.

According to an embodiment, the relay terminal device may send a datapacket containing the data to the network device. The data packet mayspecifically be a layer-2 data frame or a layer-2 PDU. The layer-2 PDUmay specifically be a MAC PDU. Or, if the user-plane protocol stack ofthe relay terminal device includes the RLC layer and the PDCP layer, thelayer-2 PDU may specifically be a MAC PDU, an RLC PDU or a PDCP PDU.

According to an embodiment, the layer-2 PDU may contain the terminaldevice identifier of the remote terminal device. The relay terminaldevice may store a corresponding relationship between an ADP-layeridentifier and a terminal device identifier. According to an embodiment,the layer-2 PDU may further contain the bearer identifier information ofthe bearer to which the data belongs, for example, bearer identifierinformation of the second bearer.

In combination with the abovementioned possible implementation mode, ina second possible implementation mode of the first aspect, a header ofthe ADP-layer PDU may contain indication information, and the indicationinformation may be configured to indicate that the data contained in theADP-layer PDU is relay data. Before the action that the relay terminaldevice forwards the data contained in the ADP-layer PDU to the networkdevice according to the acquired identifier information of the remoteterminal device, the method may further include the following actions.The relay terminal device determines that the data contained in theADP-layer PDU is required to be forwarded to the network deviceaccording to the indication information contained in the ADP-layer PDU.

According to an embodiment, the packet header of the ADP-layer PDU maycontain the indication information to indicate that the data containedin the ADP-layer PDU is relay data. Therefore, the relay terminaldevice, after receiving the ADP-layer PDU, may determine that the datacontained in the ADP-layer PDU is required to be forwarded according tothe indication information in the packet header.

According to an embodiment, the indication information in the ADP-layerPDU may give an indication explicitly or implicitly.

According to an embodiment, the relay terminal device may determinewhether the received ADP-layer PDU contains a bearer identifier field ornot to determine whether the data contained in the ADP-layer PDU isrelay data or not. For example, when the received ADP-layer PDU does notcontain the bearer identifier field, the relay terminal device maydetermine that the data contained in the ADP-layer PDU is not relay dataand is sent to the relay terminal device by the remote terminal device.For another example, when the received ADP-layer PDU contains the beareridentifier field, the relay terminal device may determine that the datacontained in the ADP-layer PDU is relay data and is required to beforwarded to the network device.

According to an embodiment, the relay terminal device may determine thebearer identifier information in the bearer identifier field in thereceived ADP-layer PDU to determine whether the data contained in theADP-layer PDU is relay data or not. For example, a relay beareridentifier range of the bearer configured for relay transmission may bepredefined or pre-configured. In such case, according to an embodiment,if the relay terminal device determines that the bearer identifierinformation contained in the received ADP-layer PDU belongs to the relaybearer identifier range, it may be determined that the data contained inthe ADP-layer PDU is relay data. According to an embodiment, if therelay terminal device determines that the bearer identifier informationcontained in the received ADP-layer PDU does not belong to the relaybearer identifier range, it may be determined that the data contained inthe ADP-layer PDU is not relay data.

In combination with the abovementioned possible implementation modes, ina third possible implementation mode of the first aspect, the actionthat the relay terminal device forwards the data contained in theADP-layer PDU to the network device according to the acquired identifierinformation of the remote terminal device includes the followingactions. The relay terminal device determines a preamble correspondingto the identifier information of the remote terminal device. The relayterminal device sends the preamble to the network device. The relayterminal device receives an uplink grant sent by the network deviceaccording to the preamble. The uplink grant contains an uplinktransmission resource allocated by the network device. The relayterminal device adopts the uplink transmission resource to send the datacontained in the ADP-layer PDU to the network device.

In combination with the abovementioned possible implementation modes, ina fourth possible implementation mode of the first aspect, the actionthat the relay terminal device forwards the data contained in theADP-layer PDU to the network device according to the acquired identifierinformation of the remote terminal device includes the followingactions. The relay terminal device sends a Buffer Status Report (BSR) tothe network device. The BSR contains the terminal device identifier ofthe remote terminal device. The relay terminal device receives aPhysical Downlink Control Channel (PDCCH) sent by the network deviceaccording to the BSR. The PDCCH is configured to schedule uplink datatransmission of the remote terminal device. The relay terminal devicesends the data contained in the ADP-layer PDU to the network deviceaccording to the PDCCH.

The PDCCH may contain the uplink grant. The relay terminal device maydetermine the uplink transmission resource allocated for the remoteterminal device by the network device according to the uplink grant inthe PDCCH and adopt the transmission resource to send the data containedin the ADP-layer PDU.

A second aspect provides another method of relay transmission, which mayinclude the following actions. A remote terminal device performsencapsulation processing on data to be sent to a network device in anADP layer of layer 2 to obtain a PDU. The ADP-layer PDU containsidentifier information of the remote terminal device. The remoteterminal device sends the ADP-layer PDU to a relay terminal device.

A third aspect provides another method of relay transmission, which mayinclude the following actions. A relay terminal device receives a datapacket sent to a remote terminal device by a network device. The relayterminal device performs encapsulation processing on data contained inthe data packet in an ADP layer of layer 2 to obtain a PDU. TheADP-layer PDU contains identifier information of the remote terminaldevice. The relay terminal device sends the ADP-layer PDU to the remoteterminal device.

According to an embodiment, the data packet may contain a terminaldevice identifier of the remote terminal device. Or the data packet maybe scheduled through a PDCCH scrambled by an RNTI of the remote terminaldevice. Or the data packet may be transmitted by adopting a transmissionresource corresponding to the remote terminal device.

According to an embodiment, the identifier information, contained in theADP-layer PDU, of the remote terminal device may include an ADP-layeridentifier of the remote terminal device or the terminal deviceidentifier of the remote terminal device.

According to an embodiment, the data packet may further contain beareridentifier information of a bearer to which the data belongs, forexample, bearer identifier information of a second bearer.Correspondingly, the ADP-layer PDU may further contain the beareridentifier information of the bearer, for example, bearer identifierinformation of a first bearer.

According to an embodiment, the data packet may specifically be alayer-2 data frame or a layer-2 PDU.

In a first possible implementation mode of the third aspect, the actionthat the relay terminal device receives the data packet sent to theremote terminal device by the network device may include the followingactions. The relay terminal device receives a layer-2 PDU sent to theremote terminal device by the network device and corresponding to asecond interface. The layer-2 PDU corresponding to the second interfacecontains the data and the second interface is a communication interfacebetween the relay terminal device and the network device.

According to an embodiment, the layer-2 PDU may specifically be a MACPDU, an RLC PDU or a PDCP PDU.

In combination with the abovementioned possible implementation mode, ina second possible implementation mode of the third aspect, the datapacket may contain a relay specific LCID; and before the actions thatthe relay terminal device performs encapsulation processing on the datacontained in the data packet in the ADP layer of layer 2 to obtain theADP-layer PDU, the method may further include the following actions. Therelay terminal device determines that the data contained in the datapacket is required to be forwarded according to the relay specific LCID.

The relay specific LCID may be configured to indicate relaytransmission.

In combination with the abovementioned possible implementation modes, ina third possible implementation mode of the third aspect, the datapacket may be scheduled by the network device through the PDCCHscrambled by a relay specific RNTI. Before the action that the relayterminal device performs encapsulation processing on the data containedin the data packet in the ADP layer of layer 2 to obtain the ADP-layerPDU, the method may further include the following actions. The relayterminal device determines that the data contained in the data packet isrequired to be forwarded according to the relay specific RNTI adoptedfor the PDCCH configured to schedule the data packet.

The relay specific RNTI may be configured to indicate relaytransmission.

A fourth aspect provides another method of relay transmission, which mayinclude the following actions. A remote terminal device receives anADP-layer PDU sent by a relay terminal device. The ADP-layer PDUcontains identifier information of the remote terminal device. Theremote terminal device acquires the identifier information, contained inthe ADP-layer PDU, of the remote terminal device in an ADP layer oflayer 2. The remote terminal device determines the remote terminaldevice corresponding to the ADP-layer PDU according to the acquiredidentifier information of the remote terminal device.

According to an embodiment, the remote terminal device may determinewhether the ADP-layer PDU is sent to it or not according to the acquiredidentifier information, contained in the ADP-layer PDU, of the remoteterminal device.

According to an embodiment, when it is determined that the ADP-layer PDUis sent to it, the remote terminal device may perform demodulationprocessing on data contained in the ADP-layer PDU.

According to an embodiment, when it is determined that the ADP-layer PDUis not sent to it, the remote terminal device may discard the ADP-layerPDU.

A fifth aspect provides a device of relay transmission, which isconfigured to execute the method in the first aspect or any possibleimplementation mode of the first aspect. Specifically, the deviceincludes units configured to execute the method in the first aspect orany possible implementation mode of the first aspect.

A sixth aspect provides another device of relay transmission, which isconfigured to execute the method in the second aspect or any possibleimplementation mode of the second aspect. Specifically, the deviceincludes units configured to execute the method in the second aspect orany possible implementation mode of the second aspect.

A seventh aspect provides another device of relay transmission, which isconfigured to execute the method in the third aspect or any possibleimplementation mode of the third aspect. Specifically, the deviceincludes units configured to execute the method in the third aspect orany possible implementation mode of the third aspect.

An eighth aspect provides another device of relay transmission, which isconfigured to execute the method in the fourth aspect or any possibleimplementation mode of the fourth aspect. Specifically, the deviceincludes units configured to execute the method in the fourth aspect orany possible implementation mode of the fourth aspect.

A ninth aspect provides another device of relay transmission, whichincludes a storage unit and a processor, wherein the storage unit isconfigured to store an instruction, the processor is configured toexecute the instruction stored in a memory, and when the processorexecutes the instruction stored in the memory, such execution enablesthe processor to execute the method in the first aspect or any possibleimplementation mode of the first aspect.

A tenth aspect provides another device of relay transmission, whichincludes a storage unit and a processor, wherein the storage unit isconfigured to store an instruction, the processor is configured toexecute the instruction stored in a memory, and when the processorexecutes the instruction stored in the memory, such execution enablesthe processor to execute the method in the second aspect or any possibleimplementation mode of the second aspect.

An eleventh aspect provides another device of relay transmission, whichincludes a storage unit and a processor, wherein the storage unit isconfigured to store an instruction, the processor is configured toexecute the instruction stored in a memory, and when the processorexecutes the instruction stored in the memory, such execution enablesthe processor to execute the method in the third aspect or any possibleimplementation mode of the third aspect.

A twelfth aspect provides another device of relay transmission, whichincludes a storage unit and a processor, wherein the storage unit isconfigured to store an instruction, the processor is configured toexecute the instruction stored in a memory, and when the processorexecutes the instruction stored in the memory, such execution enablesthe processor to execute the method in the fourth aspect or any possibleimplementation mode of the fourth aspect.

A thirteenth aspect provides a computer-readable medium, which isconfigured to store a computer program, the computer program includingan instruction configured to execute the method in the first aspect orany possible implementation mode of the first aspect.

A fourteenth aspect provides another computer-readable medium, which isconfigured to store a computer program, the computer program includingan instruction configured to execute the method in the second aspect orany possible implementation mode of the second aspect.

A fifteenth aspect provides another computer-readable medium, which isconfigured to store a computer program, the computer program includingan instruction configured to execute the method in the third aspect orany possible implementation mode of the third aspect.

A sixteenth aspect provides another computer-readable medium, which isconfigured to store a computer program, the computer program includingan instruction configured to execute the method in the fourth aspect orany possible implementation mode of the fourth aspect.

A seventeenth aspect provides a relay transmission system, whichincludes a relay terminal device, a remote terminal device and a networkdevice.

According to an embodiment, the relay terminal device may be the devicein the fifth aspect or any possible implementation mode of the fifthaspect and the remote terminal device may be the device in the sixthaspect or any possible implementation mode of the sixth aspect.

According to an embodiment, the relay terminal device may be the devicein the seventh aspect or any possible implementation mode of the seventhaspect and the remote terminal device may be the device in the eighthaspect or any possible implementation mode of the eighth aspect.

BRIEF DESCRIPTION OF DRAWINGS

In order to describe the technical solutions of the embodiments of thedisclosure more clearly, the drawings required to be used indescriptions about the embodiments of the disclosure or a conventionalart will be simply introduced below. It is apparent that the drawingsdescribed below are only some embodiments of the disclosure. Otherdrawings may further be obtained by those of ordinary skill in the artaccording to these drawings without creative work.

FIG. 1 illustrates a schematic flowchart of a wireless communicationsystem to which the embodiments of the disclosure are applied.

FIG. 2a illustrates a schematic diagram of an example of a user-planestack protocol, configured for relay transmission, of each deviceaccording to an embodiment of the disclosure.

FIG. 2b illustrates a schematic diagram of another example of auser-plane stack protocol, configured for relay transmission, of eachdevice according to an embodiment of the disclosure.

FIG. 3 illustrates a schematic flowchart of a method of relaytransmission according to an embodiment of the disclosure.

FIG. 4 illustrates a schematic flowchart of a method of relaytransmission according to another embodiment of the disclosure.

FIG. 5 illustrates a schematic block diagram of a device of relaytransmission according to an embodiment of the disclosure.

FIG. 6 illustrates a schematic block diagram of another device of relaytransmission according to an embodiment of the disclosure.

FIG. 7 illustrates a schematic block diagram of another device of relaytransmission according to an embodiment of the disclosure.

FIG. 8 illustrates a schematic block diagram of another device of relaytransmission according to an embodiment of the disclosure.

FIG. 9 illustrates a schematic block diagram of another device of relaytransmission according to an embodiment of the disclosure.

FIG. 10 illustrates a schematic block diagram of another device of relaytransmission according to an embodiment of the disclosure.

DETAILED DESCRIPTION

The technical solutions in the embodiments of the disclosure will beclearly and completely described below in combination with the drawingsin the embodiments of the disclosure. It is apparent that the describedembodiments are not all embodiments but part of embodiments of thedisclosure. All other embodiments obtained by those of ordinary skill inthe art on the basis of the embodiments in the disclosure withoutcreative work shall fall within the scope of protection of thedisclosure.

It should be understood that terms “system” and “network” in thedisclosure may usually be exchanged in the disclosure. In thedisclosure, term “and/or” is only an association relationship describingassociated objects and represents that three relationships may exist.For example, A and/or B may represent three conditions: i.e.,independent existence of A, existence of both A and B and independentexistence of B. In addition, character “/” in the disclosure usuallyrepresents that previous and next associated objects form an “or”relationship.

FIG. 1 illustrates a schematic diagram of a wireless communicationsystem 100 to which the embodiments of the disclosure are applied. Thewireless communication system 100 may include at least one networkdevice 110. The network device 110 may be a device communicating with aterminal device. Each network device 100 may provide communicationcoverage for a specific geographical region and may communicate with aterminal device located in the coverage. The network device 110 may be aBase Transceiver Station (BTS) in a Global System of Mobilecommunication (GSM) or a Code Division Multiple Access (CDMA) system,may also be a NodeB (NB) in a Wideband Code Division Multiple Access(WCDMA) system, and may further be an Evolutional Node B (eNB or eNodeB)in an LTE system or a wireless controller in a Cloud Radio AccessNetwork (CRAN). Or the network device may be a relay station, an accesspoint, a vehicle-mounted device, a wearable device, a network-sidedevice in a future 5th-Generation (5G) network, a network device in afuture evolved Public Land Mobile Network (PLMN) or the like.

The wireless communication system 100 further includes multiple terminaldevices 120 located within the coverage of the network device 110. Theterminal devices 120 may be mobile or fixed. The terminal device 120 mayrefer to an access terminal, User Equipment (UE), a user unit, a userstation, a mobile station, a mobile radio station, a remote station, aremote terminal, a mobile device, a user terminal, a terminal, awireless communication device, a user agent or a user device. The accessterminal may be a cell phone, a cordless phone, a Session InitiationProtocol (SIP) phone, a Wireless Local Loop (WLL) station, a PersonalDigital Assistant (PDA), a handheld device with a wireless communicationfunction, a computing device, another processing device connected to awireless modem, a vehicle-mounted device, a wearable device, a terminaldevice in the future 5G network, a terminal device in the future evolvedPLMN or the like.

A network device and six terminal devices are exemplarily illustrated inFIG. 1. According to an embodiment, the wireless communication system100 may include multiple network devices and another number of terminaldevices may be included in coverage of each network device. There are nolimits made thereto in the embodiments of the disclosure. In addition,the wireless communication system 100 may further include anothernetwork entity such as a Mobile Management Entity (MME), a ServingGateway (S-GW) and a Packet data Network Gateway (P-GW). However, theembodiments of the disclosure are not limited thereto.

Specifically, the terminal device 120 may communicate in a cellularcommunication mode or a D2D communication mode. In the cellularcommunication mode, the terminal device may communicate with anotherterminal device through the network device. In the D2D communicationmode, the terminal device may directly communicate with another terminaldevice through a D2D link.

In the multiple terminal devices 120 illustrated in FIG. 1, a cellularterminal device 1 and cellular terminal device 2 which adopt a cellularcommunication technology to communicate with the network device 110, aD2D terminal device 1 and D2D terminal device 2 which perform datatransmission with the network device through relay terminal devices, arelay terminal device 1 and a relay terminal device 2 are exemplarilyillustrated. The relay terminal devices may implement relay transmissionof uplink data sent to the network device by the D2D terminal devices orrelay transmission of downlink data sent to the D2D terminal devices bythe network device. Between the relay terminal devices and the D2Dterminal devices, there may be first interfaces, for example, PC5interfaces, and a D2D communication technology is adopted forcommunication. The D2D communication technology may specifically be anSL technology in LTE, may also be a Wireless Fidelity (WIFI) orBluetooth technology in a Wireless Local Area Network (WLAN) or isanother D2D communication technology. There are no limits made theretoin the embodiments of the disclosure. Between the relay terminal devicesand the network device, there may be second interfaces, for example, Uuinterfaces, and a cellular communication technology is adopted forcommunication. For convenient understanding, descriptions will be madewith the condition that the first interfaces are specifically PC5interfaces and the second interfaces are specifically Uu interfacesbelow. However, the first interfaces and the second interfaces may alsospecifically be other names. There are no limits made thereto in theembodiments of the disclosure.

In the conventional art, a relay terminal device adopts a layer-3 relaymanner for relay, which results in a relatively long data processingdelay. In the embodiments of the disclosure, the relay terminal devicesmay adopt a layer-1 or layer-2 relay manner to relay data transmissionbetween the network device and the D2D terminal devices. In such case, amanner of layer-1 data frame or layer-2 PDU may be adopted for relaydata transmitted at the Uu interfaces and a layer-2 PDU may be adoptedfor relay data transmitted at the PC5 interface. However, theembodiments of the disclosure are not limited thereto.

FIG. 2a and FIG. 2b schematically illustrate examples of a user-planeprotocol stack, configured for relay transmission, of each devicerespectively. As illustrated in FIG. 2a , user-plane protocol stacks,configured for relay transmission, of a D2D terminal device, a relayterminal device and a network device may include layer 1 or layer 2.Layer 1 and layer 2, corresponding to a PC5 interface, of the relayterminal device and layer 1 and layer 2, corresponding to the PC5interface, of the D2D terminal device are mutually equivalent layersrespectively. Layer 1 and layer 2, corresponding to a Uu interface, ofthe relay terminal device and layer 1 and layer 2, corresponding to theUu interface, of the network device are mutually equivalent layersrespectively. In such case, the user-plane protocol stacks, configuredfor relay transmission, of the relay terminal device, the network deviceand the D2D terminal device may not include layer 3. However, theembodiments of the disclosure are not limited thereto.

Specifically, in Uu interface User-plane (Uu-U) protocol stacks of therelay terminal device and the network device, layer 1 may specificallybe a PHY layer and layer 2 may include a MAC layer, an RLC layer and aPDCP layer. In PC5 interface User-plane (PC5-U) stack protocols of therelay terminal device and the D2D terminal device, a relatively lowlayer (for example, layer 1, or layer 1 and a bottom layer of layer 2)may correspond to a specific D2D communication technology adopted on thePC5 interface. For example, if the D2D communication technology isspecifically an SL technology of LTE, the relatively low layer in thePC5-U stack protocol may include a PHY layer and a MAC layer. If the D2Dcommunication technology is specifically a WIFI technology, therelatively low layer in the PC5-U protocol stack may include the PHYlayer and a MAC sublayer, etc. The embodiments of the disclosure are notlimited thereto.

As illustrated in FIG. 2a , in the PC5-U stack protocol of theembodiments of the disclosure, for recognizing the D2D terminal device,an ADP layer may be added. The ADP layer may be configured to recognizeand encapsulate relay data. Specifically, the ADP layer may beconfigured to recognize identifier information of the D2D terminaldevice, for example, an ADP-layer identifier of the D2D terminal device,or may also be configured to recognize a relay specific LCID configuredto indicate relay transmission. In addition, the ADP layer may beconfigured to convert data which is received from a lower layer andtransmitted by adopting various D2D communication technologies into aform irrelevant to the D2D communication technology and further transmitthe processed data to an upper layer for processing. Similarly, the ADPlayer may further be configured to encapsulate data transmitted by theupper layer into a form corresponding to the D2D communicationtechnology adopted for the PC5 interface and may transmit theencapsulated data to the lower layer, for example, transmitted to thebottom layer of layer 2 and layer 1. Therefore, the PC5 interface maysupport various D2D communication technologies.

According to an embodiment, the ADP layer may be located above thebottom layer of layer 2. The bottom layer of layer 2 may correspond tothe D2D communication technology adopted for the PC5 interface.Specifically, in FIG. 2a , the ADP layer is located between the bottomlayer of layer 2 and the RLC layer. According to an embodiment, the ADPlayer may also be located between the RLC layer and the PDCP layer or atanother position of layer 2. There are no limits made thereto in theembodiments of the disclosure.

FIG. 2b schematically illustrates another example of the user-planeprotocol stack, configured for relay transmission, of each device. Adifference between FIG. 2b and FIG. 2a is that: in FIG. 2b , theuser-plane protocol stack of the relay terminal device does not includethe RLC layer and the PDCP layer; and correspondingly, the RLC layer ofthe D2D terminal device and the RLC layer of the network device aremutually equivalent layers and the PDCP layer of the D2D terminal deviceand the PDCP layer of the network device are mutually equivalent layers.In such case, the relay terminal device, when relaying data between theD2D terminal device and the network device, may not perform analyticalprocessing on the data. However, the embodiments of the disclosure arenot limited thereto.

It is to be noted that the examples of FIG. 2a to FIG. 2b are adoptednot to limit the scope of the embodiments of the disclosure but only tohelp those skilled in the art to better understand the embodiments ofthe disclosure. It is apparent that those skilled in the art may makevarious equivalent modifications or variations according to the examplesof FIG. 2a and FIG. 2b , and such modifications or variations shall alsofall within the scope of the embodiments of the disclosure.

FIG. 3 schematically illustrates a method 200 of relay transmissionaccording to an embodiment of the disclosure. The method 200 may beapplied to the wireless communication system 100. However, theembodiment of the disclosure is not limited thereto. Specifically, themethod 200 may be applied to relay transmission of uplink data. That is,a D2D terminal device (which may also be called a remote terminaldevice) transmits the uplink data to a network device through a relayterminal device.

In S210, a remote terminal device performs encapsulation processing ondata to be sent in an ADP layer of layer 2 to generate an ADP-layer PDU.

According to an embodiment, if the ADP layer is located above a bottomlayer of layer 2, the remote terminal device may perform encapsulationprocessing on the data to be sent through the ADP layer, or may alsoperform encapsulation processing through an RLC layer or sequentiallythrough a PDCP layer and the RLC layer before performing encapsulationprocessing through the ADP layer. There are no limits made thereto inthe embodiment of the disclosure. When encapsulation processing isperformed on the data to be sent through the ADP layer, the remoteterminal device may add identifier information of the remote terminaldevice to the data to be sent to obtain the ADP-layer PDU and maytransmit the ADP-layer PDU to the bottom layer of layer 2 for furtherencapsulation processing. However, the embodiment of the disclosure isnot limited thereto.

According to an embodiment, the identifier information of the remoteterminal device may include a terminal device identifier of the remoteterminal device. The terminal device identifier may be configured touniquely identify the remote terminal device. The terminal deviceidentifier may be predefined. For example, the terminal deviceidentifier may specifically be a device identifier of the remoteterminal device or a user identifier of the remote terminal device, etc.Or, the identifier information of the remote terminal device may includean ADP-layer identifier of the remote terminal device, i.e., anidentifier for encapsulation and analysis in the ADP layer. TheADP-layer identifier of the remote terminal device may be configured touniquely identify the remote terminal device during relay transmission.The ADP-layer identifier of the remote terminal device may be predefinedand may also be configured by a network device. For example, theADP-layer identifier of the remote terminal device is allocated for theremote terminal device by the network device in a process ofestablishing a bearer for the remote terminal device. However, theembodiment of the disclosure is not limited thereto.

According to an embodiment, the remote terminal device may furthercontain indication information configured to indicate that the datacontained in the ADP-layer PDU is relay data in the ADP-layer PDU. Thatis, the indication information may be configured to indicate that thedata contained in the ADP-layer PDU is not sent to the relay terminaldevice and is required to be forwarded to the network device by therelay terminal device.

According to an embodiment, the indication information in the ADP-layerPDU may give an indication explicitly or implicitly. The indicationinformation may occupy one or more bits.

According to an embodiment, in the embodiment of the disclosure, abearer identifier field may be contained or not contained in theADP-layer PDU to indicate whether the data contained in the ADP-layerPDU is relay data or not. Correspondingly, when the relay terminaldevice receives the ADP-layer PDU sent by the remote terminal device,whether the ADP-layer PDU contains the bearer identifier field or notmay be determined. As an optional example, if the ADP-layer PDU does notcontain the bearer identifier field, the relay terminal device maydetermine that the data contained in the ADP-layer PDU is not relay dataand is sent to the relay terminal device by the remote terminal device.According to an embodiment, if the ADP-layer PDU contains the beareridentifier field, the relay terminal device may determine that the datacontained in the ADP-layer PDU is relay data and is required to beforwarded to the network device. However, the embodiment of thedisclosure is not limited thereto.

According to an embodiment, in the embodiment of the disclosure, therelay terminal device may also recognize bearer identifier informationin the bearer identifier field in the ADP-layer PDU to determine whetherthe data contained in the ADP-layer PDU is relay data or not. Forexample, a relay bearer identifier range of a bearer configured forrelay transmission may be predefined or pre-configured. In such case,according to an embodiment, if the relay terminal device determines thatthe bearer identifier information contained in the received ADP-layerPDU belongs to the relay bearer identifier range, it may be determinedthat the data contained in the ADP-layer PDU is relay data. According toan embodiment, if the relay terminal device determines that the beareridentifier information contained in the received ADP-layer PDU does notbelong to the relay bearer identifier range, it may be determined thatthe data contained in the ADP-layer PDU is not relay data. However, theembodiment of the disclosure is not limited thereto.

According to an embodiment, the ADP-layer PDU may further contain thebearer identifier information of the bearer to which the data to be sentbelongs. The bearer identifier information may include a beareridentifier or an LCID. There are no limits made thereto in theembodiment of the disclosure.

In S220, the remote terminal device sends the ADP-layer PDU to a relayterminal device.

According to an embodiment, the remote terminal device may furtherprocess the ADP-layer PDU in layer 1 and send the processed ADP-layerPDU to the relay terminal device through a PC5 interface with the relayterminal device. However, the embodiment of the disclosure is notlimited thereto.

According to an embodiment, if a network side configures a transmissionresource, for example, a time-frequency resource, a code-domain resourceand/or a space-domain resource, configured for relay transmission forthe remote terminal device, the remote terminal device may send theADP-layer PDU to the relay terminal device through the transmissionresource configured for relay transmission. In such case, the relayterminal device may determine that the data contained in the ADP-layerPDU is relay data according to the transmission resource occupied by theADP-layer PDU. According to an embodiment, the remote terminal devicemay further indicate that the data contained in the ADP-layer PDU isrelay data in another manner. There are no limits made thereto in theembodiment of the disclosure.

In S230, the relay terminal device receives the ADP-layer PDU sent bythe remote terminal device, acquires identifier information, containedin the ADP-layer PDU, of the remote terminal device in an ADP layer and,in S240, forwards the data contained in the ADP-layer PDU to a networkdevice according to the acquired identifier information of the remoteterminal device.

The relay terminal device may analyze the identifier information,contained in the received ADP-layer PDU, of the remote terminal devicein the ADP layer. According to an embodiment, if a user-plane protocolstack, corresponding to the PC5 interface, of the relay terminal devicefurther includes an RLC layer and a PDCP layer, the relay terminaldevice may further transmit the ADP-layer PDU to the RLC layer and thePDCP layer for further analytical processing.

Specifically, the relay terminal device may recognize the identifierinformation, contained in the received ADP-layer PDU, of the remoteterminal device, for example, the ADP-layer identifier of the remoteterminal device, in the ADP layer to determine the remote terminaldevice corresponding to the ADP-layer PDU. The relay terminal device mayalso perform encapsulation processing on the data contained in theADP-layer PDU according to the acquired identifier information of theremote terminal device to obtain a data packet corresponding to a Uuinterface. The data packet may specifically be a layer-1 data frame or alayer-2 PDU and the data packet is sent to the network device throughthe Uu interface.

In the embodiment of the disclosure, the layer-1 data frame may refer tothat encapsulation processing is performed on the data only throughlayer 1 and encapsulation processing of a higher layer is not performed.The layer-2 PDU may refer to that an outermost layer or highest layer ofthe data is encapsulated in layer 2 of the device. According to anembodiment, in a user-plane stack protocol corresponding to the Uuinterface, layer 2 may include a MAC layer, an RLC layer and a PDCPlayer. Correspondingly, the layer-2 PDU may specifically refer to a MACPDU, an RLC PDU or a PDCP PDU. The MAC PDU may be obtained by performingencapsulation processing on the data only through the MAC layer in layer2 without encapsulation processing of the RLC layer and the PDCP layer.The RLC PDU may be obtained by performing encapsulation processing onthe data sequentially through the RLC layer and the PDCP layer in layer2 without encapsulation processing of the PDCP layer. The PDCP PDU maybe obtained by performing encapsulation processing on the datasequentially through the PDCP layer, the RLC layer and the MAC layer inlayer 2. There are no limits made thereto in the embodiment of thedisclosure.

According to an embodiment, the data packet may contain the terminaldevice identifier of the remote terminal device. For example, the relayterminal device may determine the terminal device identifiercorresponding to the ADP-layer identifier contained in the ADP-layer PDUaccording to a pre-stored corresponding relationship between a terminaldevice identifier and an ADP-layer identifier and contain the determinedterminal device identifier in the data packet. However, the embodimentof the disclosure is not limited thereto.

According to an embodiment, the data packet may also contain the beareridentifier information of the bearer to which the data to be sentbelongs. However, the embodiment of the disclosure is not limitedthereto.

According to an embodiment, before the relay terminal device sends thedata packet to the network device, the relay terminal device may furtherinitiate an uplink grant request and adopt an uplink transmissionresource allocated by the network device to send the data packet to thenetwork device.

As an optional embodiment, the relay terminal device may send ascheduling request to the network device. The scheduling request isconfigured to request the network device to allocate the uplinktransmission resource for the relay terminal device. The network device,after receiving the scheduling request, may send an uplink grant to therelay terminal device. The uplink grant is configured to indicate theuplink transmission resource allocated for the relay terminal device bythe network device. The relay terminal device, after receiving theuplink grant, may adopt the uplink transmission resource to send thedata packet to the network device.

As another optional embodiment, the relay terminal device may determinea preamble allocated for the remote terminal device by the networkdevice at first. For example, the relay terminal device may determinethe preamble corresponding to the identifier information, contained inthe ADP-layer PDU, of the remote terminal device according to acorresponding relationship between an ADP-layer identifier or a terminaldevice identifier and a preamble. Then, the relay terminal device maysend the preamble to the network device to initiate an uplink grantrequest flow. The network device, after receiving the preamble sent bythe relay terminal device, may send the uplink grant to the relayterminal device and, after receiving the data packet transmitted byadopting the uplink transmission resource indicated by the uplink grantfrom the relay terminal device, determines the remote terminal devicecorresponding to the data packet. In such case, according to anembodiment, the data packet may not contain the terminal deviceidentifier of the remote terminal device. Therefore, signaling overheadmay further be saved.

As another optional embodiment, the relay terminal device may send a BSRto the network device to initiate the uplink grant request. The BSR maycontain the terminal device identifier of the remote terminal device.The network device, after receiving the BSR, may send a PDCCH to therelay terminal device to schedule uplink data transmission of the remoteterminal device. The relay terminal device, after receiving the PDCCH,may send the data packet to the network device according to the PDCCH.The network device, after receiving the data packet sent by the relayterminal device, may determine the remote terminal device correspondingto the data packet according to the PDCCH configured to schedule thedata packet. In such case, according to an embodiment, the data packetmay not contain the terminal device identifier of the remote terminaldevice. However, the embodiment of the disclosure is not limitedthereto.

Therefore, according to the method of relay transmission of theembodiment of the disclosure, the remote terminal device sends theADP-layer PDU to the relay terminal device, the ADP-layer PDU containingthe identifier information of the remote terminal device, and the relayterminal device may recognize the identifier information, contained inthe ADP-layer PDU, of the remote terminal device in the ADP layer andforward the data contained in the ADP-layer PDU according to theidentifier information of the remote terminal device. Compared with alayer-3 relay manner adopted by the relay terminal device in theconventional art, such a manner may reduce processing complexity of therelay terminal device, reduce a transmission delay of relay data andimprove overall performance of a system.

FIG. 4 schematically illustrates a method 300 of relay transmissionaccording to another embodiment of the disclosure. The method 300 may beapplied to relay transmission of downlink data. That is, a networkdevice transmits the downlink data to a remote terminal device through arelay terminal device.

In S310, a network device performs encapsulation processing on data tobe sent to generate a data packet. The data packet may specifically be alayer-1 data frame or layer-2 PDU corresponding to a Uu interface.

According to an embodiment, the layer-2 PDU may specifically be a MACPDU, an RLC PDU or a PDCP PDU. There are no limits made thereto in theembodiment of the disclosure.

According to an embodiment, the data packet may contain a terminaldevice identifier of a remote terminal device.

According to an embodiment, the data packet may contain a relay specificLCID. The relay specific LCID may be configured to indicate that thedata contained in the data packet is relay data and is required to beforwarded by a relay terminal device. According to an embodiment, therelay specific LCID may be preset and may also be pre-allocated by thenetwork device. For example, the network device allocates the relayspecific LCID in a process of establishing a bearer for the remoteterminal device. However, the embodiment of the disclosure is notlimited thereto.

According to an embodiment, the network device schedules the data packetthrough a PDCCH scrambled by a relay specific RNTI. The relay specificRNTI may be predefined or allocated for the remote terminal device bythe network device and, for example, is allocated for the remoteterminal device by the network device in the process of establishing thebearer for the remote terminal device. However, there are no limits madethereto in the embodiment of the disclosure.

In S320, the network device sends the data packet to a relay terminaldevice through the Uu interface.

In S330, the relay terminal device receives the data packet sent by thenetwork device and performs encapsulation processing on the datacontained in the data packet in an ADP layer obtain an ADP-layer PDU,the ADP-layer PDU containing identifier information of the remoteterminal device.

The relay terminal device may perform analytical processing on the datapacket to determine the remote terminal device corresponding to the datapacket. According to an embodiment, if the data packet contains theterminal device identifier of the remote terminal device, the relayterminal device may determine the remote terminal device correspondingto the data packet according to the terminal device identifier,contained in the data packet, of the remote terminal device. However,the embodiment of the disclosure is not limited thereto.

The relay terminal device may perform encapsulation processing on thedata contained in the data packet through the ADP layer to obtain theADP-layer PDU. According to an embodiment, the relay terminal device mayobtain the ADP-layer PDU by encapsulation processing of the ADP layerand a bottom layer in layer 2 and also by encapsulation processing of aPDCP layer and an RLC layer before encapsulation processing of the ADPlayer. After encapsulation processing of the ADP layer, the relayterminal device may transmit the data to the bottom layer for furtherencapsulation processing. However, the embodiment of the disclosure isnot limited thereto.

According to an embodiment, the identifier information of the remoteterminal device may include the terminal device identifier of the remoteterminal device. Or the identifier information of the remote terminaldevice may include an ADP-layer identifier of the remote terminaldevice. However, the embodiment of the disclosure is not limitedthereto.

According to an embodiment, the ADP-layer PDU may further contain beareridentifier information of the remote terminal device. There are nolimits made thereto in the embodiment of the disclosure.

According to an embodiment, the ADP-layer PDU may further containidentifier information of the relay terminal device. There are no limitsmade thereto in the embodiment of the disclosure.

According to an embodiment, before the ADP-layer PDU is generated, therelay terminal device may further determine that the data contained inthe data packet is relay data and is required to be forwarded.Specifically, if the data packet contains the relay specific LCID, therelay terminal device may determine that the data contained in the datapacket is required to be forwarded according to the relay specific LCID.Or, if the data packet is scheduled through the PDCCH scrambled by therelay specific RNTI, the relay terminal device may determine that thedata contained in the data packet is required to be forwarded accordingto the PDCCH configured to schedule the data packet. According to anembodiment, the relay terminal device may further determine that thedata contained in the data packet is relay data in another manner. Thereare no limits made thereto in the embodiment of the disclosure.

In S340, the relay terminal device sends the ADP-layer PDU to the remoteterminal device.

According to an embodiment, the relay terminal device may send theADP-layer PDU through a transmission resource configured for relaytransmission. However, the embodiment of the disclosure is not limitedthereto.

In S350, the remote terminal device receives the ADP-layer PDU sent bythe relay terminal device and acquires the identifier information,contained in the ADP-layer PDU, of the remote terminal device in an ADPlayer to determine whether the ADP-layer PDU is sent to it or not.

According to an embodiment, if the identifier information contained inthe ADP-layer PDU is matched with the identifier of the remote terminaldevice, the remote terminal device may determine that the ADP-layer PDUis sent to it and may further perform demodulation processing on thedata contained in the ADP-layer PDU. According to an embodiment, if theidentifier information contained in the ADP-layer PDU is mismatched withthe identifier of the remote terminal device, the remote terminal devicemay determine that the ADP-layer PDU is not sent to it and may discardthe ADP-layer PDU. However, the embodiment of the disclosure is notlimited thereto.

Therefore, according to the method of relay transmission of theembodiment of the disclosure, the relay terminal device, after receivingthe data packet sent by the network device, may perform encapsulationprocessing on the data contained in the data packet to obtain theADP-layer PDU, the ADP-layer PDU containing the identifier informationof the remote terminal device, and send the ADP-layer PDU to the remoteterminal device, and the remote terminal device may analyze theidentifier information, contained in the received ADP-layer PDU, of theremote terminal device in the ADP layer and accordingly determinewhether the ADP-layer PDU is sent to it or not. Compared with a layer-3relay manner adopted by the relay terminal device in the conventionalart, such a manner may reduce processing complexity of the relayterminal device, reduce a transmission delay of relay data and improveoverall performance of a system.

It should be understood that magnitudes of sequence numbers of eachprocess are not intended to represent an execution sequence and theexecution sequence of each process should be determined by theirfunctions and internal logic and shall not form any limit to animplementation process of the embodiments of the disclosure.

The method of relay transmission according to the embodiments of thedisclosure is described above in combination with FIG. 1 to FIG. 4 indetail. A device of relay transmission according to the embodiments ofthe disclosure will be described below in combination with FIG. 5 toFIG. 10 in detail.

FIG. 5 illustrates a device 400 of relay transmission according to anembodiment of the disclosure. The device 400 includes a receiving unit410, processing unit 420 and sending unit 430 which are sequentiallycoupled.

In an optional embodiment, the device 400 may be applied to relaytransmission of uplink data.

The receiving unit 410 may be configured to receive an ADP-layer PDUsent to a network device by a remote terminal device, the ADP-layer PDUcontaining identifier information of the remote terminal device and theADP-layer PDU being obtained by performing, by the remote terminaldevice, encapsulation processing on data contained in the ADP-layer PDUin an ADP layer of layer 2.

The processing unit 420 may be configured to acquire the identifierinformation, contained in the ADP-layer PDU received by the receivingunit 410, of the remote terminal device in an ADP layer of layer 2.

The sending unit 430 may be configured to forward the data contained inthe ADP-layer PDU to the network device according to the identifierinformation, acquired by the processing unit 420, of the remote terminaldevice.

According to an embodiment, the identifier information of the remoteterminal device may include an ADP-layer identifier of the remoteterminal device or a terminal device identifier of the remote terminaldevice.

According to an embodiment, the processing unit 420 is furtherconfigured to generate a layer-2 PDU corresponding to a second interfaceaccording to the identifier information of the remote terminal device,the second interface being a communication interface between the device400 and the network device.

Correspondingly, the sending unit 430 is specifically configured to sendthe layer-2 PDU, generated by the processing unit 420, corresponding tothe second interface to the network device.

According to an embodiment, a header of the ADP-layer PDU may containindication information. The indication information is configured toindicate that the data contained in the ADP-layer PDU is relay data. Insuch case, the processing unit 420 may further be configured to, beforethe sending unit 430 forwards the data contained in the ADP-layer PDU tothe network device according to the acquired identifier information ofthe remote terminal device, determine that the data contained in theADP-layer PDU is required to be forwarded to the network deviceaccording to the indication information contained in the ADP-layer PDU.

In another optional embodiment, the device 400 may be applied to relaytransmission of downlink data.

The receiving unit 410 may be configured to receive a data packet sentto the remote terminal device by the network device.

According to an embodiment, the data packet may specifically be alayer-2 data frame or a layer-2 PDU.

The processing unit 420 may be configured to perform encapsulationprocessing on data contained in the data packet received by thereceiving unit 410 in the ADP layer of layer 2 to obtain the ADP-layerPDU, the ADP-layer PDU containing the identifier information of theremote terminal device.

The sending unit 430 may be configured to send the ADP-layer PDUobtained by the processing unit 420 to the remote terminal device.

According to an embodiment, the receiving unit 410 may specifically beconfigured to receive the layer-2 PDU sent to the remote terminal deviceby the network device and corresponding to the second interface, thelayer-2 PDU corresponding to the second interface containing the dataand the second interface being the communication interface between thedevice and the network device.

According to an embodiment, the data packet contains a relay specificLCID. In such case, the processing unit 420 may further be configuredto, before encapsulation processing is performed on the data containedin the data packet in the ADP layer of layer 2 to obtain the ADP-layerPDU, determine that the data contained in the data packet is required tobe forwarded according to the relay specific LCID.

According to an embodiment, the data packet is scheduled by the networkdevice through a PDCCH scrambled by a relay specific RNTI. In such case,the processing unit 420 may further be configured to, beforeencapsulation processing is performed on the data contained in the datapacket in the ADP layer of layer 2 to obtain the ADP-layer PDU,determine that the data contained in the data packet is required to beforwarded according to the relay specific RNTI adopted for the PDCCHconfigured to schedule the data packet.

In the embodiment of the disclosure, a communication interface betweenthe device 400 and the remote terminal device may be a first interface.

According to an embodiment, in a user-plane protocol stack,corresponding to the first interface, of the device 400, layer 2 mayonly include a bottom layer and the ADP layer located above the bottomlayer. Or, in the user-plane protocol stack, corresponding to the firstinterface, of the device 400, layer 2 may include the bottom layer, theADP layer, an RLC layer and a PDCP layer. The ADP layer is locatedbetween the RLC layer and the bottom layer.

According to an embodiment, in the user-plane stack protocolcorresponding to the first interface, a layer located below the ADPlayer may correspond to a D2D communication technology adopted betweenthe device and the remote terminal device.

Specifically, the layer located below the ADP layer may include layer 1and the bottom layer of layer 2.

In an optional example, the device 400 may specifically be the relayterminal device in the abovementioned embodiments and the device 400 maybe configured to execute each flow and/or step corresponding to therelay terminal device in the abovementioned method embodiments, whichwill not be elaborated herein for avoiding repetitions.

FIG. 6 illustrates a device 500 of relay transmission according to anembodiment of the disclosure. The device 500 may be applied to relaytransmission of uplink data. The device 500 includes a processing unit510 and a sending unit 520.

The processing unit 510 is configured to perform encapsulationprocessing on data to be sent to a network device in an ADP layer oflayer 2 to obtain an ADP-layer PDU, the ADP-layer PDU containingidentifier information of the device 500.

The sending unit 520 is configured to send the ADP-layer PDU generatedby the processing unit 510 to a relay terminal device.

According to an embodiment, the identifier information of the device 500includes an ADP-layer identifier of the device 500 or a terminal deviceidentifier of the device 500.

A communication interface between the relay terminal device and thedevice 500 may specifically be a first interface.

According to an embodiment, in a user-plane protocol stack,corresponding to the first interface, of the relay terminal device,layer 2 may only include a bottom layer and an ADP layer located abovethe bottom layer. Or, in the user-plane protocol stack, corresponding tothe first interface, of the relay terminal device, layer 2 includes thebottom layer, the ADP layer, an RLC layer and a PDCP layer. The ADPlayer is located between the RLC layer and the bottom layer.

According to an embodiment, in the user-plane stack protocolcorresponding to the first interface, a layer located below the ADPlayer may correspond to a D2D communication technology adopted betweenthe relay terminal device and the device 500.

According to an embodiment, a header of the ADP-layer PDU containsindication information. The indication information is configured toindicate that the data contained in the ADP-layer PDU is relay data.

According to an embodiment, the ADP-layer PDU further contains beareridentifier information of a bearer to which the data belongs.

In an optional example, the device 500 may specifically be the remoteterminal device in the abovementioned embodiments and the device 500 maybe configured to execute each flow and/or step corresponding to theremote terminal device in the abovementioned method embodiments, whichwill not be elaborated herein for avoiding repetitions.

FIG. 7 illustrates a device 600 of relay transmission according to anembodiment of the disclosure. The device 600 may be applied to relaytransmission of downlink data. The device 600 includes a receiving unit610 and a processing unit 620.

The receiving unit 610 is configured to receive an ADP-layer PDU sent bya relay terminal device, the ADP-layer PDU containing identifierinformation of the device 600.

The processing unit 620 is configured to acquire the identifierinformation, contained in the ADP-layer PDU received by the receivingunit 610, of the device 600 in an ADP layer of layer 2 and determine theremote terminal device corresponding to the ADP-layer PDU according tothe acquired identifier information of the device 600.

According to an embodiment, the identifier information of the device 600includes an ADP-layer identifier of the device 600 or a terminal deviceidentifier of the device 600.

A communication interface between the relay terminal device and thedevice 600 is a first interface.

According to an embodiment, in a user-plane protocol stack,corresponding to the first interface, of the relay terminal device,layer 2 may only include a bottom layer and an ADP layer located abovethe bottom layer. Or, in the user-plane protocol stack, corresponding tothe first interface, of the relay terminal device, layer 2 includes thebottom layer, the ADP layer, an RLC layer and a PDCP layer. The ADPlayer is located between the RLC layer and the bottom layer.

According to an embodiment, in the user-plane stack protocolcorresponding to the first interface, a layer located below the ADPlayer may correspond to a D2D communication technology adopted betweenthe relay terminal device and the device 600.

In an optional example, the device 600 may specifically be the remoteterminal device in the abovementioned embodiments and the device 600 maybe configured to execute each flow and/or step corresponding to theremote terminal device in the abovementioned method embodiments, whichwill not be elaborated herein for avoiding repetitions.

FIG. 8 illustrates a device 700 of relay transmission according to anembodiment of the disclosure. The device 700 includes a receiver 710,processor 720 and sender 730 which are sequentially coupled.

In an optional embodiment, the device 700 may be applied to relaytransmission of uplink data.

The receiver 710 may be configured to receive an ADP-layer PDU sent to anetwork device by a remote terminal device, the ADP-layer PDU containingidentifier information of the remote terminal device and the ADP-layerPDU being obtained by performing, by the remote terminal device,encapsulation processing on data contained in the ADP-layer PDU in anADP layer of layer 2.

The processor 720 may be configured to acquire the identifierinformation, contained in the ADP-layer PDU received by the receiver710, of the remote terminal device in an ADP layer of layer 2.

The sender 730 may be configured to forward the data contained in theADP-layer PDU to the network device according to the identifierinformation, acquired by the processor 720, of the remote terminaldevice.

According to an embodiment, the identifier information of the remoteterminal device may include an ADP-layer identifier of the remoteterminal device or a terminal device identifier of the remote terminaldevice.

According to an embodiment, the processor 720 is further configured togenerate a layer-2 PDU corresponding to a second interface according tothe identifier information of the remote terminal device, the secondinterface being a communication interface between the device 700 and thenetwork device.

Correspondingly, the sender 730 is specifically configured to send thelayer-2 PDU, generated by the processor 720, corresponding to the secondinterface to the network device.

According to an embodiment, a header of the ADP-layer PDU may containindication information. The indication information is configured toindicate that the data contained in the ADP-layer PDU is relay data. Insuch case, the processor 720 may further be configured to, before thesender 730 forwards the data contained in the ADP-layer PDU to thenetwork device according to the acquired identifier information of theremote terminal device, determine that the data contained in theADP-layer PDU is required to be forwarded to the network deviceaccording to the indication information contained in the ADP-layer PDU.

In another optional embodiment, the device 700 may be applied to relaytransmission of downlink data.

The receiver 710 may be configured to receive a data packet sent to theremote terminal device by the network device.

According to an embodiment, the data packet may specifically be alayer-1 data frame or a layer-2 PDU.

The processor 720 may be configured to perform encapsulation processingon data contained in the data packet received by the receiver 410 in theADP layer of layer 2 to obtain the ADP-layer PDU, the ADP-layer PDUcontaining the identifier information of the remote terminal device.

The sender 730 may be configured to send the ADP-layer PDU obtained bythe processor 720 to the remote terminal device.

According to an embodiment, the receiver 710 may specifically beconfigured to receive the layer-2 PDU sent to the remote terminal deviceby the network device and corresponding to the second interface, thelayer-2 PDU corresponding to the second interface containing the dataand the second interface being the communication interface between thedevice and the network device.

According to an embodiment, the data packet contains a relay specificLCID. In such case, the processor 720 may further be configured to,before encapsulation processing is performed on the data contained inthe data packet in the ADP layer of layer 2 to obtain the ADP-layer PDU,determine that the data contained in the data packet is required to beforwarded according to the relay specific LCID.

According to an embodiment, the data packet is scheduled by the networkdevice through a PDCCH scrambled by a relay specific RNTI. In such case,the processor 720 may further be configured to, before encapsulationprocessing is performed on the data contained in the data packet in theADP layer of layer 2 to obtain the ADP-layer PDU, determine that thedata contained in the data packet is required to be forwarded accordingto the relay specific RNTI adopted for the PDCCH configured to schedulethe data packet.

In the embodiment of the disclosure, a communication interface betweenthe device 700 and the remote terminal device may be a first interface.

According to an embodiment, in a user-plane protocol stack,corresponding to the first interface, of the device 700, layer 2 mayonly include a bottom layer and the ADP layer located above the bottomlayer. Or, in the user-plane protocol stack, corresponding to the firstinterface, of the device 700, layer 2 may include the bottom layer, theADP layer, an RLC layer and a PDCP layer. The ADP layer is locatedbetween the RLC layer and the bottom layer.

According to an embodiment, in the user-plane stack protocolcorresponding to the first interface, a layer located below the ADPlayer may correspond to a D2D communication technology adopted betweenthe device and the remote terminal device.

Specifically, the layer located below the ADP layer may include layer 1and the bottom layer of layer 2.

It should be understood that the device 700 may specifically be therelay terminal device in the abovementioned embodiments and may beconfigured to execute each step and/or flow corresponding to the relayterminal device in the abovementioned method embodiments. According toan embodiment, the device 700 may further include a memory. The memorymay include a Read-Only Memory (ROM) and a Random Access Memory (RAM)and provides an instruction and data for the processor. A part of thememory may further include a nonvolatile RAM. For example, the memorymay further store information of a device type. The processor may beconfigured to execute the instruction stored in the memory. When theprocessor executes the instruction stored in the memory, the processoris configured to execute each step and/or flow of the abovementionedmethod embodiments.

FIG. 9 illustrates a device 800 of relay transmission according to anembodiment of the disclosure. The device 800 may be applied to relaytransmission of uplink data. The device 800 includes a processor 810 anda sender 820.

The processor 810 is configured to perform encapsulation processing ondata to be sent to a network device in an ADP layer of layer 2 to obtainan ADP-layer PDU, the ADP-layer PDU containing identifier information ofthe device 800.

The sender 820 is configured to send the ADP-layer PDU generated by theprocessor 810 to a relay terminal device.

According to an embodiment, the identifier information of the device 800includes an ADP-layer identifier of the device 800 or a terminal deviceidentifier of the device 800.

A communication interface between the relay terminal device and thedevice 800 may specifically be a first interface.

According to an embodiment, in a user-plane protocol stack,corresponding to the first interface, of the relay terminal device,layer 2 may only include a bottom layer and an ADP layer located abovethe bottom layer. Or, in the user-plane protocol stack, corresponding tothe first interface, of the relay terminal device, layer 2 includes thebottom layer, the ADP layer, an RLC layer and a PDCP layer. The ADPlayer is located between the RLC layer and the bottom layer.

According to an embodiment, in the user-plane stack protocolcorresponding to the first interface, a layer located below the ADPlayer may correspond to a D2D communication technology adopted betweenthe relay terminal device and the device 800.

According to an embodiment, a header of the ADP-layer PDU containsindication information. The indication information is configured toindicate that the data contained in the ADP-layer PDU is relay data.

According to an embodiment, the ADP-layer PDU further contains beareridentifier information of a bearer to which the data belongs.

It should be understood that the device 800 may specifically be theremote terminal device in the abovementioned embodiments and may beconfigured to execute each step and/or flow corresponding to the remoteterminal device in the abovementioned method embodiments. According toan embodiment, the device 800 may further include a memory. The memorymay include a ROM and a RAM and provides an instruction and data for theprocessor. A part of the memory may further include a nonvolatile RAM.For example, the memory may further store information of a device type.The processor may be configured to execute the instruction stored in thememory. When the processor executes the instruction stored in thememory, the processor is configured to execute each step and/or flow ofthe abovementioned method embodiments.

FIG. 10 illustrates a device 900 of relay transmission according to anembodiment of the disclosure. The device 900 may be applied to relaytransmission of downlink data. The device 900 includes a receiver 910and a processor 920.

The receiver 910 is configured to receive an ADP-layer PDU sent by arelay terminal device, the ADP-layer PDU containing identifierinformation of the device 900.

The processor 920 is configured to acquire the identifier information,contained in the ADP-layer PDU received by the receiver 910, of thedevice 900 in an ADP layer of layer 2 and determine the remote terminaldevice corresponding to the ADP-layer PDU according to the acquiredidentifier information of the device 900.

According to an embodiment, the identifier information of the device 900includes an ADP-layer identifier of the device 900 or a terminal deviceidentifier of the device 900.

A communication interface between the relay terminal device and thedevice 900 is a first interface.

According to an embodiment, in a user-plane protocol stack,corresponding to the first interface, of the relay terminal device,layer 2 may only include a bottom layer and an ADP layer located abovethe bottom layer. Or, in the user-plane protocol stack, corresponding tothe first interface, of the relay terminal device, layer 2 includes thebottom layer, the ADP layer, an RLC layer and a PDCP layer. The ADPlayer is located between the RLC layer and the bottom layer.

According to an embodiment, in the user-plane stack protocolcorresponding to the first interface, a layer located below the ADPlayer may correspond to a D2D communication technology adopted betweenthe relay terminal device and the device 900.

It should be understood that the device 900 may specifically be theremote terminal device in the abovementioned embodiments and may beconfigured to execute each step and/or flow corresponding to the remoteterminal device in the abovementioned method embodiments. According toan embodiment, the device 900 may further include a memory. The memorymay include a ROM and a RAM and provides an instruction and data for theprocessor. A part of the memory may further include a nonvolatile RAM.For example, the memory may further store information of a device type.The processor may be configured to execute the instruction stored in thememory. When the processor executes the instruction stored in thememory, the processor is configured to execute each step and/or flow ofthe abovementioned method embodiments.

It should be understood that, in the embodiments of the disclosure, theprocessor may be a Central Processing Unit (CPU) and the processor mayalso be another universal processor, a Digital Signal Processor (DSP),an Application Specific Integrated Circuit (ASIC), a Field-ProgrammableGate Array (FPGA) or another programmable logic device, discrete gate ortransistor logic device and discrete hardware component and the like.The universal processor may be a microprocessor or the processor mayalso be any conventional processor and the like.

An embodiment of the disclosure further provides a wirelesscommunication system, which may include a relay terminal device, remoteterminal device and network device in any abovementioned embodiment.

It should be understood that, in the disclosure, the descriptions aboutthe embodiments are made with emphasis on differences between eachembodiment and the same or similar parts may refer to each other andwill not be elaborated herein for simplicity.

In an implementation process, each step of the method may be completedby an integrated logic circuit of hardware in the processor or aninstruction in a software form. The steps of the method disclosed incombination with the embodiments of the disclosure may be directlyembodied to be executed and completed by a hardware processor orexecuted and completed by a combination of hardware and software modulesin the processor. The software module may be located in a mature storagemedium in this field such as a RAM, a flash memory, a ROM, aProgrammable ROM (PROM) or Electrically PROM (EPROM) and a register. Thestorage medium is located in the memory, and the processor reads theinstruction in the memory, and completes the steps of the method incombination with hardware. No more detailed descriptions will be madeherein to avoid repetitions.

It should be understood that, in the disclosure, the descriptions aboutthe embodiments are made with emphasis on differences between eachembodiment and the same or similar parts may refer to each other toavoid repetitions.

Those of ordinary skill in the art may realize that the steps and unitsof each method described in combination with the embodiments disclosedin the disclosure may be implemented by electronic hardware, computersoftware or a combination of the two. For clearly describingexchangeability of hardware and software, the steps and compositions ofeach embodiment have been generally described in the foregoingdescriptions according to functions. Whether these functions areexecuted in a hardware or software manner depends on specificapplications and design constraints of the technical solutions. Those ofordinary skill in the art may realize the described functions for eachspecific application by virtue of different methods, but suchrealization shall fall within the scope of the disclosure.

Those skilled in the art may clearly learn about that specific workingprocesses of the system, device and unit described above may refer tothe corresponding processes in the method embodiments and will not beelaborated herein for convenient and brief description.

In some embodiments provided by the application, it should be understoodthat the disclosed system, device and method may be implemented inanother manner. For example, the device embodiment described above isonly schematic, and for example, division of the units is only logicfunction division, and other division manners may be adopted duringpractical implementation. For example, multiple units or components maybe combined or integrated into another system, or some characteristicsmay be neglected or not executed. In addition, coupling or directcoupling or communication connection between each displayed or discussedcomponent may be indirect coupling or communication connection,implemented through some interfaces, of the device or the units, and maybe electrical and mechanical or adopt other forms.

The units described as separate parts may or may not be physicallyseparated, and parts displayed as units may or may not be PHY units, andnamely may be located in the same place, or may also be distributed tomultiple network units. Part or all of the units may be selected toachieve the purpose of the solutions of the embodiments of thedisclosure according to a practical requirement.

In addition, each functional unit in each embodiment of the disclosuremay be integrated into a processing unit, each unit may also physicallyexist independently, and two or more than two units may also beintegrated into a unit. The integrated unit may be implemented in ahardware form and may also be implemented in form of software functionalunit.

When being implemented in form of software functional unit and sold orused as an independent product, the integrated unit may be stored in acomputer-readable storage medium. Based on such an understanding, thetechnical solutions of the disclosure substantially or parts makingcontributions to the conventional art or all or part of the technicalsolutions may be embodied in form of software product, and the computersoftware product is stored in a storage medium, including a plurality ofinstructions configured to enable a computer device (which may be apersonal computer, a server, a network device or the like) to executeall or part of the steps of the method in each embodiment of thedisclosure. The abovementioned storage medium includes: various mediacapable of storing program codes such as a U disk, a mobile hard disk, aROM, a RAM, a magnetic disk or an optical disk.

The above is only the specific implementation mode of the disclosure andnot intended to limit the scope of protection of the disclosure. Variousequivalent modifications or replacements are apparent to those skilledin the art within the technical scope disclosed by the disclosure shallfall within the scope of protection of the disclosure and thesemodifications or replacements shall fall within the scope of protectionof the disclosure. Therefore, the scope of protection of the disclosureshall be subject to the scope of protection of the claims.

1. A method of relay transmission, comprising: receiving, by a relayterminal device, an ADPtive (ADP)-layer Protocol Data Unit (PDU) sent toa network device by a remote terminal device, the ADP-layer PDUcontaining identifier information of the remote terminal device and theADP-layer PDU being obtained through performing, by the remote terminaldevice, encapsulation processing on data contained in the ADP-layer PDUin an ADP layer of layer 2; acquiring, by the relay terminal device, theidentifier information, contained in the ADP-layer PDU, of the remoteterminal device in an ADP layer of layer 2; and forwarding, by the relayterminal device according to the acquired identifier information of theremote terminal device, the data contained in the ADP-layer PDU to thenetwork device.
 2. The method of claim 1, wherein the identifierinformation of the remote terminal device comprises an ADP-layeridentifier of the remote terminal device or a terminal device identifierof the remote terminal device.
 3. The method of claim 1, wherein, in auser-plane protocol stack, corresponding to a first interface, of therelay terminal device, layer 2 only comprises a bottom layer and the ADPlayer located above the bottom layer; or in the user-plane protocolstack, corresponding to the first interface, of the relay terminaldevice, layer 2 comprises the bottom layer, the ADP layer, a Radio LinkControl (RLC) layer and a Packet Data Convergence Protocol (PDCP) layer,the ADP layer being located between the RLC layer and the bottom layer,wherein the first interface is a communication interface between therelay terminal device and the remote terminal device.
 4. The method ofclaim 1, wherein, in the user-plane protocol stack corresponding to thefirst interface, a layer located below the ADP layer corresponds to aDevice-to-Device (D2D) communication technology adopted between therelay terminal device and the remote terminal device.
 5. The method ofclaim 1, wherein forwarding, by the relay terminal device according tothe acquired identifier information of the remote terminal device, thedata contained in the ADP-layer PDU to the network device comprises:generating, by the relay terminal device according to the identifierinformation of the remote terminal device, a layer-2 PDU correspondingto a second interface, the second interface being a communicationinterface between the relay terminal device and the network device; andsending, by the relay terminal device, the layer-2 PDU corresponding tothe second interface to the network device.
 6. The method of claim 1,wherein a header of the ADP-layer PDU contains indication information,and the indication information is configured to indicate that the datacontained in the ADP-layer PDU is relay data; and before forwarding, bythe relay terminal device according to the acquired identifierinformation of the remote terminal device, the data contained in theADP-ayer PDU to the network device, the method further comprises:determining, by the relay terminal device according to the indicationinformation contained in the ADP-layer PDU, that the data contained inthe ADP-layer PDU is required to be forwarded to the network device. 7.The method of claim 1, wherein the ADP-layer PDU further contains beareridentifier information of a bearer to which the data belongs. 8-13.(canceled)
 14. A method of relay transmission, comprising: receiving, bya relay terminal device, a data packet sent to a remote terminal deviceby a network device; performing, by the relay terminal device,encapsulation processing on data contained in the data packet in anADPtive (ADP) layer of layer 2 to obtain an ADP-layer Protocol Data Unit(PDU), the ADP-layer PDU containing identifier information of the remoteterminal device; and sending, by the relay terminal device, theADP-layer PDU to the remote terminal device.
 15. The method of claim 14,wherein the identifier information of the remote terminal devicecomprises an ADP-layer identifier of the remote terminal device or aterminal device identifier of the remote terminal device.
 16. The methodof claim 14, wherein, in a user-plane protocol stack, corresponding to afirst interface, of the relay terminal device, layer 2 only comprises abottom layer and the ADP layer located above the bottom layer; or in theuser-plane protocol stack, corresponding to the first interface, of therelay terminal device, layer 2 comprises the bottom layer, the ADPlayer, a Radio Link Control (RLC) layer and a Packet Data ConvergenceProtocol (PDCP) layer, the ADP layer being located between the RLC layerand the bottom layer, wherein the first interface is a communicationinterface between the relay terminal device and the remote terminaldevice.
 17. The method of claim 14, wherein, in the user-plane protocolstack corresponding to the first interface, a layer located below theADP layer corresponds to a Device-to-Device (D2D) communicationtechnology adopted between the relay terminal device and the remoteterminal device.
 18. The method of claim 14, wherein receiving, by therelay terminal device, the data packet sent to the remote terminaldevice by the network device comprises: receiving, by the relay terminaldevice, a layer-2 PDU sent to the remote terminal device by the networkdevice and corresponding to a second interface, the layer-2 PDUcorresponding to the second interface containing the data and the secondinterface being a communication interface between the relay terminaldevice and the network device.
 19. The method of claim 14, wherein thedata packet contains a relay specific Logical Channel Identifier (LCID);and before performing, by the relay terminal device, encapsulationprocessing on the data contained in the data packet in the ADP layer oflayer 2 to obtain the ADP-layer PDU, the method further comprises:determining, by the relay terminal device according to the relayspecific LCID, that the data contained in the data packet is required tobe forwarded.
 20. The method of claim 14, wherein the data packet isscheduled by the network device through a Physical Downlink ControlChannel (PDCCH) scrambled by a relay specific Radio Network TemporaryIdentity (RNTI); and before performing, by the relay terminal device,encapsulation processing on the data contained in the data packet in theADP layer of layer 2 to obtain the ADP-layer PDU, the method furthercomprises: determining, by the relay terminal device according to therelay specific RNTI adopted for the PDCCH configured to schedule thedata packet, that the data contained in the data packet is required tobe forwarded.
 21. The method of claim 14, wherein the ADP-layer PDUfurther contains bearer identifier information of a bearer to which thedata belongs. 22-25. (canceled)
 26. A device of relay transmission,comprising a processor and one or more units stored on a memory, the oneor more units comprising: a receiving unit, configured to receive anADPtive (ADP)-layer Protocol Data Unit (PDU) sent to a network device bya remote terminal device, the ADP-layer PDU containing identifierinformation of the remote terminal device and the ADP-layer PDU beingobtained by performing, by the remote terminal device, encapsulationprocessing on data contained in the ADP-layer PDU in an ADP layer oflayer 2; a processing unit, configured to acquire the identifierinformation, contained in the ADP-layer PDU received by the receivingunit, of the remote terminal device in an ADP layer of layer 2; and asending unit, configured to forward the data contained in the ADP-layerPDU to the network device according to the identifier information,acquired by the processing unit, of the remote terminal device.
 27. Thedevice of claim 26, wherein the identifier information of the remoteterminal device comprises an ADP-layer identifier of the remote terminaldevice or a terminal device identifier of the remote terminal device.28. The device of claim 26, wherein, in a user-plane protocol stack,corresponding to a first interface, of the device, layer 2 onlycomprises a bottom layer and the ADP layer located above the bottomlayer; or in the user-plane protocol stack, corresponding to the firstinterface, of the device, layer 2 comprises the bottom layer, the ADPlayer, a Radio Link Control (RLC) layer and a Packet Data ConvergenceProtocol (PDCP) layer, the ADP layer being located between the RLC layerand the bottom layer, wherein the first interface is a communicationinterface between the device and the remote terminal device.
 29. Thedevice of claim 26, wherein, in the user-plane protocol stackcorresponding to the first interface, a layer located below the ADPlayer corresponds to a Device-to-Device (D2D) communication technologyadopted between the device and the remote terminal device.
 30. Thedevice of claim 26, wherein the processing unit is further configured togenerate a layer-2 PDU corresponding to a second interface according tothe identifier information of the remote terminal device, the secondinterface being a communication interface between the device and thenetwork device; and the sending unit is configured to send the layer-2PDU, generated by the processing unit, corresponding to the secondinterface to the network device. 31-50. (canceled)